Obturating means for a firearm



E. M. HARVEY 2,889,748 OBTURATING MEANS FOR A FIRERM n Filed Nov. v, 1957 `lune 9, 1959 l m E fm T v l Nv m m Om\ V ON @N N H l (K/ E |fi I @m.. r 1 lm g @vw @w X n NN /mm /mw Nm Nm Ew -MumHmw.

Q mm @v [wm il NN /vm mv om :mim h IEM United States Patent 2,889,748 j oBTURATlNG MEANS FOR A FIREARM Earle M. Harvey, Agawam, Mass., assignor tothe United States of America as represented by the Secretary of the Army Application November 7, 1957, Serial No. 695,181 2 'Claims (Cl. 89-26) i (Granted under Title 35, U.S. Code (1952), sec. 266) The invention described hereinmay be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to those firearms in which the ring chamber is provided vin a member which is movable relative to the barrel.

With those firearms in'which the propellant is discharged in a' chamber which is located in a member, `movable relative to the barrel, and is separate therefrom, the problem of sealing the junction between the chamber and barrel bore is acute as the escape of gases thereby presents a hazardous condition.

It is, therefore, an object of this invention to provide a firearm structure whereby obturation between the barrel and the firing chamber, carried in a separate member, is increased with an increase in gas pressure produced in the firing chamber and, thereby, is particularly well suited to those firearms which use high pressure propellant.

It is another object of this invention to provide for such firearm structure obturating means which prevents the escape of gases between the barrel and the firing chamber and is actuatable by opposing movement produced in a pair of slidably related members forming the tiring chamber when a propellant is discharged therein with such relative movement being transferred to the obturating means by a dilference in the relative resiliency of the receiver and the member carrying the firing chamber.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 is a longitudinal cross-sectional view of a lirearm structure embodying the invention with the parts g shown in normal battery position; and

Fig. 2 is a View similar to Fig. 1 but showing the relationship of the parts when the firearm is fired.

For illustrative purposes, the invention is shown embodied in a firearm structure which uses a liquid propellant and is provided with a receiver 12 having a longitudinally-disposed cylindrical opening 14 therethrough. Mounted in the front end of opening 14 is a barrel assembly 16 comprising a barrel 18 which is joined against relative displacement to receiver 12 by a cylindrical adapter 20 which surrounds the breech portion of the barrel so that the rear end of such adapter and barrel are planarly aligned. The breech end of barrel 18 is countersunk to form a conical recess 22.

A cylindrical member 24 having a diameter similar to that of opening 14 and carrying a ring chamber 26 is slidably mounted in such opening rearwardly of barrel 18. Provided in the front end of member 24 is a conical obturating portion 28 which is receivable in recess 22 to provide a gas-tight connection between barrel 18 and member 24 when such barrel and member are forced toward each other. With obturating portion 28 engaged with the walls of recess 22, a clearance is provided between the barrel assembly 16 and the remaining portion frice of the front end of member 24 so that forward movement of 'such member may press the obturating portion more firmly lagainst the wall of the recess. A lock ring 30 is rotatably received by an annular recess 31 in the rear end ofreceiver 12 so as to be engageable with the rear end of member 24. Such ring 30 is provided with a conventional cam means (not shown) which is engageable with the rear end of member 24 to cammingly press such member forwardly and force obturating portion 28 into recess 22 when such lock ring is rotated and to secure such member against rearward displacement relative to the receiver.

Member 24 is longitudinally bored, as noted at 25, to form a large diameter portion 32 at the rear end with a concentric portion 34 of smaller diameter extending forwardly therefrom. The junction of portions 32 and 34 forms an annular flange 36. The walls of bore 25, forward of portion 34, taper inwardly to a concentric aperture 40 to form a tapered section 38 which defines the front portion of firing chamber 26. Aperture 40 extends axially` through` obturating portion 28 to communicate with the bore of barrel 18 and has a diameter similar to that of such bore.

An assembly 42 carrying a ring mechanism 44 is installed within member 24 from the rear end thereof. Assembly 42 includes a cylindrical insert 46 having a body portion 48 receivable by large diameter portion 32 and a neck portion 50 receivable by small diameter portion 34. The junction of body portion 48 and neck portion 50 forms an annular shoulder 52 which is engageable with flange 36, and such body and neck portions have diameters similar to those portions of bore 25 in which they are received. A cylindrical block 54 is threadably mounted in larger diameter portion 32 rearwardly of insert 46 to threadably press shoulder 52 forwardly against ilange 36 and to provide a rear buttress for insert 46. A reduced diameter portion 45 of block 54 projects rearwardly from an annular shoulder 57 for extension through lock ring 30 and a retainer 59 is threadably mounted to the end of reduced diameter portion 45 to secure such lock ring against annular shoulder 57 and to engage lock ring 30 therebetween. Thereby, the rear end of member 2.4 is xedly connected to receiver 12 as such rear end is threadably engaged to block 54 and lock ring 30, engaged between retainer 59 and shoulder 57, is mounted in recess 31 of receiver 12. Provided in the front end of neck portion 56 is a substantially semispherical recess 56 which, with the tapered section 3S, forms the firing chamber 26 and a tubular portion 62. The outside of member 24 is reduced in diameter, as noted at 64, to reduce the thickness of the walls surrounding larger diameter portion 32 so that the longitudinal resilience of such member is greater than that of receiver 12.

Thus, when liquid propellant is discharged in firing chamber 26 by iring mechanism 44, the resulting gas pressure presses forwardly against the walls of the tapered section 38, rearwardly against insert 46 and outwardly against the walls of tubular portion 62 while propelling a projectile along the bore of barrel 18. The rearward force exerted against insert 46 is transferred through block 54 and lock ring 30 to receiver 12 and, therefore, to barrel 18, which is also joined against relative displacement to such receiver, and through block 54 to the rear end of member 24 which is connected by thread means thereto. Consequently, the pressure which acts oppositely against tapered section 38 of member 24 and insert 46 produces converging forces respective to barrel 18 and the front end of such member. By reducing the thickness of the walls of member 24 at reduced diameter portion 64 so that the longitudinal resilience of the member is greater than that of receiver 12 the opposing forces applied to the member and insert 46 press the front end of member 24 and the breech end of barrel 18 together with a force determined by the pressure of the gases produced in firing chamber 26 and the diierence in the longitudinal resiliency of reduced diameter section 64 over that of the walls of receiver 12 between ring 30 and adapter 20. Thus, obturating portion 218 and recess 22 are forcible into tighter engagement, because of the `space provided between member Z4 and barrel 18, so that when the gas pressure generated in ring chamber 26 is increased, the efficiency of the obturation provided by the engagement of the obturating portion and recess is increased proportionally. Further, the outward pressure applied against the tubular portion 62 presses the outside surface of neck portion 50 against the wall of smaller diameter portion 34 to prevent the escape of gases between member 24 and insert 46.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

l. A firearm structure including a receiver, a barrel with a bore, means for xedly mounting said barrel to the front end of said receiver, a member slidingly disposed within said receiver, means for xedly joining the rear end of said member to the rear end of said receiver, a tapered section in the front end of said member, an insert slidingly disposed within said member, means for securing said insert against rearward displacement relative to the rear end of said member, a firing chamber formed by a semispherical recess in the front end of said insert and by said tapered section, an aperture extending from said firing chamber through said member for communication with said bore, cooperating obturating means provided integrally in said barrel and on said member to form a gas-tightA connection between said aperture and said bore according to the pressure generated in said tiring chamber and the difference in the longitudinal resiliency of said member over that of said receiver.

2. The structure of claim l and including a section of said member reduced in dimension to increase the longitudinal resilience thereof over that of said receiver to increase the eliciency of said obturating means.

References Cited in the file of this patent UNITED STATES PATENTS 1,965,637 Frederich et al July 10, 1934 FOREIGN PATENTS 624,405 Great Britain June 8, 1949 1,003,687 France Nov. 21, 1951 679,269 Great Britain Sept. 17, 1952 

